Question: Solve the equation. $ 20 = r + 11$ $r=$
Solution: Subtract $11$ from both sides: 20 − 11 20 − 11 = = r r + 11 − 11 \begin{eqnarray}20 &=& r &+ 11 \\ \\ {-11} && &{-11} \\\\ 20 {- 11} &=& r \end{eqnarray} Simplifying, we get: $ r = 9$